Door checking and controlling device

ABSTRACT

A DOOR CONTROLLING APPARATUS INCORPORATED IN AND DESIGNED TO CONTROL THE OPENING AND CLOSING OF DOORS, PARTICULARLY HEAVY DOORS OF THE TYPES COMMONLY USED IN FACTORIES. THE APARATUS PERFORMS SEVERAL CONTROLLING FUNCTIONS, INCLUDING HOLDING THE DOOR IN A CLOSED POSITION UNTIL A PREDETERMINED OPENING TORQUE IS APPLIED TO THE DOOR, ALLOWING RELATIVE EASE OF CONTINUED OPENING OF THE DOOR COMPARED TO THE TORQUE REQUIRED TO INITIATE OPENING, BRAKING THE OPENING SWING OF THE DOOR AT A PREDETERMINED POINT, AND MAINTAINING THE DOOR IN AN OPEN POSITION FOR A PREDETERMINED PERIOD OF TIME PRIOR TO CLOSING THE DOOR IN A CONTROLLED MANNER. ALL OF THESE FUNCTIONS ARE PERFORMED UTILIZING THE ENERGY APPLIED TO OPEN THE DOOR.

Sept. 20, 1971 NOLAN ETAL 3,605,340

DOOR CHECKING AND CONTROLLING DEVICE Filed Feb. 2, 1970 2 Sheets-Sheet 1 INVIiNI (1R5 JOHN E OLA/v Ewan/ J IPL INGER W Jig/w) 4M Sept. 20, 1971 NOLAN ETAL 3,605,340

DOOR CHECKING AND CONTROLLING DEVICE Filed Feb. 3, 1970 2 Sheets-Sheet 2 F 521:;fl izvimmu3' 'IN HNIURS JOHN .NozJ /v BYQUDOLPHJIV/PL/NGEE 147 TOR/V1575 United States Patent DOOR CHECKING AND CONTROLLING DEVICE John E. Nolan and Rudolph J. Wiplinger, St. Paul, Minn.,

assignors to Minnnesota Mining and Manufacturing Company, St. Paul, Minn.

Filed Feb. 2, 1970, Ser. No. 7,802 Int. Cl. E05f N00 US. Cl. 49-387 18 Claims ABSTRACT OF THE DISCLOSURE A door controlling apparatus incorporated in and designed to control the opening and closing of doors, particularly heavy doors of the types commonly used in factories. The apparatus performs several controlling functions, including holding the door in a closed position until a predetermined opening torque is applied to the door, allowing relative ease of continued opening of the door compared to the torque required to initiate opening, braking the opening swing of the door at a predetermined point, and maintaining the door in an open position for a predetermined period of time prior ,to closing the door in a controlled manner. All of these functions are performed utilizing the energy applied to open the door.

BACKGROUND OF THE INVENTION This invention relates to an apparatus for controlling the pattern of opening and closing of a door, and in one aspect relates to an apparatus for controlling the opening and closing of a heavy factory door through which door pass personnel and/or vehicles such as fork lift trucks utilized in afactory.

The prior art is replete with door controlling and closing apparatus which alford varying measures of control over the pattern of opening and closing of a door through which door personnel pass as in a business establishment or an oflice building. Typical examples of the prior art for door control apparatus are disclosed in US. Pat. Nos. 3,409,934; 3,408,683; 3,358,318; 3,246,362; 3,222,709; 3,216,056; 3,174,177; 3,156,002; 3,137,888; 3,079,629; 3,078,500; 3,064,964; and 3,042,957. While the mechanics utilized in the listed patents vary slightly, generally these patents disclose an apparatus to be used on a door and comprise a spring in which a portion of the energy manually provided to open the door is stored so that the door subsequently may be closed by the spring. The closing pattern of the door is generally controlled by a hydraulic means which slows the closing swing of the door, as the door approaches its closed position, so that objectionable slamming of the door will not occur. Some of the apparatuses also provide a detent means to allow the door to be retained at a full open position, from which open position the door may be again closed by manually starting the closing action.

The types of mechanisms disclosed in the previously listed patents are also often designed to be recessed into the door or door frame for appearance reasons, which is consistent with their intended use in pedestrian doors such as doors in stores or office buildings.

While the previously listed door control mechanisms may serve for pedestrian doors which receive relatively small abuse and which are manually held open as people pass through them, the useful application of such door control mechanisms does not extend to the heavy factory door typically used in industry, as the mechanisms disclosed in the listed patents are in most cases too delicate for such use, and their functions are not consistent with the use of a factory door for reasons now to be explained.

3,605,340 Patented Sept. 20, 1971 ICC Typically, factory doors are hung in pairs in a frame, each door swinging in both directions from within the frame so that the factory workers and the vehicles of the factory, such as the fork lift truck, may pass through from either direction. Typically, a fork lift truck weighing 3,000 pounds, traveling about 8 miles per hour, and carrying on its bifurcated forward projecting prongs a load of up to 3,000 pounds will strike more or less the center of the doors in an attempt to fling them sufficiently open so that the full length of the load and truck may pass through before the centering springs of the door again drive the door closed. The attempt is generally in vain and the door bounces and scrapes along a large portion of the load and/or truck, possibly damaging truck, door, and/or load. Hinge damage is also common from such violent opening of the factory doors as the side of the door along a vertical line a short distance from the hinge axis may strike the edge of the frame and becomes the pivot point for the further opening travel of the door, thereby distorting or breaking the hinges.

Another problem often encountered with doors leading to the outside of factories is that strong winds may hold double swinging factory doors slightly ajar, thereby permitting cold breezes to enter resulting in discomfort of workers within. This problem exists because the spring return door hinges commonly in use on factory doors offer but small resistance to small angles of door movement from the closed position, and the large wind load area of a factory door therefore allows the wind to open the door slightly. While stronger door centering springs might be utilized to aleviate this problem, this approach would magnify the aforementioned problems involved in moving extended loads through such doors. Additionally, such strong centering springs would make the doors even more difficult to use for personnel and manually propelled vehicle passage than is the case with the normal energy storing centering springs commonly in use.

Thus, it can be seen that there is a need for a rugged door and door controlling mechanism which can stand the abuse of heavy factory usage, maintain a closed position against extraneous opening forces or wind loading, for the benefit of non-motorized trafiic allow relative ease of opening subsequent to the initial opening torque requirements and provide a self-contained braking system which will absorb excess opening energy to stop the opening swing of the door at a predetermined point, lock the door in the open position for a predetermined period of time, and subsequently close the door in a controlled manner. The present invention meets all these needs.

One prior art door controlling apparatus for similar service is disclosed in US. PatqNo. 2,916,762 issued Dec. 15, 19 59, which apparatus is a device for checking a door used in plants, garages, warehouses or the like. This apparatus provides a spring biased follower and a cam which is attached to the shaft about which the door rotates and a detent on the camis engaged by the follower to hold the door in the closed position until a predetermined opening torque is applied to the door. This apparatus also provides for restraining the opening swing of a door when the cam directly engages the strong spring biasing the follower at a predetermined point in the opening swing of the door. Additionally, the apparatus slows the initial closing motion of the door from the open position. This prior art device, however, fails to disclose a device to hold a door in a fixed open position for a predetermined period of time after a predetermined open position is reached. Also, the prior art device in restraining the opening swing of a door transfers the excess energy of the opening door to a restraining spring,

which spring subsequently applies the energy so stored to the door as a closing torque. This closing torqne operates to overcome the hydraulic damping. device which tends to initially slow the closing motion of the door, thus, the energy so stored in the spring tends to negate the desirable feature of initial slowed closing of the door. Note also that the closing motion of the door is only slowed and the door is not held open in one position after the opening swing of the door is stopped. Thus, long vehicles or successive loads may be struck by the door to damage the load, vehicle and/or doors.

SUMMARY OF THE INVENTION The device of the present invention provides a braking means which overcomes at a predetermined angle the further opening of the door to prevent possible damage to the door and its mountings. The braking means in the present invention, unlike the prior art, dissipates the excess energy of the opening door in stopping the opening motion of the door except for an amount of energy used to activate a mechanical brake on the door. The mechanical brake on the door may be retained in an activated condition for a predetermined time after the opening swing of the door has stopped and may com- I pletely delay the closing swing of the door for a predetermined time. The feature of holding the door in the open position for a predetermined time is not present in the prior art and is important where long or successive loads repeatedly pass through a factory door.

The present invention affords the advantage of greater automatic control over the door movements. The apparatus of the present invention provides an initial opening resistance and a brake for the door to control the extent to which it is opened when opening torques are applied thereto. Once opened to the extent afforded by the brake, the door may be held open for a predetermined interval before being closed under the closing forces applied thereto by the apparatus. Additionally, the rate of closing movement is controlled. Also, the mechanism of the present invention utilized to maintain the door in the closed position against wind loads or other potential opening forces is easily adjusted to meet the varying requirements of initial opening torque.

The door checking and controlling device of the present invention is adapted to be utilized in combination with the door and frame and comprises a door hinge and support frame adapted to be fixed to the door, a stationary brake member and cam member adapted to be fixed to the frame, and a cam follower adapted to be attached to the door and movable about said cam member for actuating, against a biasing force, an hydraulically actuating dash pot means for a mechanical friction brake engageable with said brake member, and means for controlling the operation of said actuating dash pot means. The actuating dash pot means and biasing means is substantially all supported within said support frame for the door to avoid the use of flexible fluid lines and exposed parts which may be damaged in the normal use of the door.

BRIEF DESCRIPTION OF THE DRAWING The above and added advantages of the present invention will be more apparent after reading the following detailed description which refers to the accompanying drawing wherein:

FIG. 1 is a front vertical view in perspective of a pair of doors incorporating the door checking and controlling device of the present invention;

FIG. 2 is a fragmentary vertical view, partially in section, of the upper half of a door incorporating a door checking and closing device of the present invention;

FIG. 3 is a fragmentary vertical view, partially in section, of the lower half of a door which incorporates the present invention;

FIG. 4 is a sectional plan view of a door incorporating the present invention, which view was taken approximately along the line 4- 4 of FIG. 2;

FIG. 5 is a fragmentary detail sectional view, partially in section, of the dash pot portion of the door checking and controlling device of the present invention as it would appear when the door is in the open position; and

FIG. 6 is a sectional, horizontal, detail view taken approximately along the line 6-6 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a door assembly including a pair of swinging factory doors 110 fitted with spring steel bumpers 11 to help absorb the impact of vehicles, such as fork lift trucks, passing through. Each of the doors is fitted with a door checking and controlling device according to the present invention. Also, each door 10 is mounted for movement from a closed position to an open position in two directions in relationship to a frame 12 by a door hinge means illustrated as a pair of bearings 13 journalling the opposing ends and aligned with the axis of a hollow tubular support frame or cylinder 15 attached to the vertical edge of the door 10 which is adjacent the side of the frame '12, as can be best seen in FIGS. 2 and 3. The cylinder 15 encloses a hydraulic damping and actuating system and a biasing means for the closing mechanism of the device of this invention. The cylinder 15 also serves as a liquid reservior for reasons which will later be described. The upper portion of the cylinder 15 is telescoped into a sleeve 16 which facilitates assembly and mounting of the door and door frame.

The door checking and controlling device includes means for retaining the door 10 in the closed position by resisting movement of the doors 10 from the closed position until a predetermined minimum torque is ap plied to the door 10.

The means defining the closed position and resisting movement from the closed position is illustrated in FIGS. 1 through 4 and comprises cam means rotatably attached to the door frame [12 and illustrated herein as a pair of sheaves 18 (FIG. 4) located with their axes spaced equally from and parallel to the axis of the hinge means of the door 10. The sheaves 18 are spaced equally one on each side of the door frame 12 and the door 10 when the door 10 is in the closed position. An annular cam follower 19 attached to the door 10 locates the door 10 in the closed position with points on the periphery of the follower 19 in contact with a point on the periphery of each sheave 1 8 on the side of the sheaves 18 opposite the axis about which the door 10 swings. The follower 19 is rotatably attached to a pivoted bar 20. The bar 20 is pivotally mounted for movement in the plane of the door on a pin 21 and pivots in a short are above the door 10 so that follower 19 moves in a direction or path essentially normal to the axis about which the door 10 swings, the path being thus oriented essentially at a right angle to the direction in which the door moves. A cable 22 is attached at one end to the follower 19, and passes through the nip of the sheaves 18, over guide means illustrated as a pulley 23 rotatably mounted on the door frame 12 above the door pivot, through an opening in the center of the mounting for the top bearing 13 along the door pivot axis into the cylinder 15. The other end of the cable 22 fits through a pipe cap 24, attached to a pipe 25 and has an enlarged end to prevent separation. The pipe 25 has a felt washer 26 fixed about the pipe within the cylinder 15 to serve as a dust seal and guide. The pipe 25 is attached at its end opposite the pipe cap 24 to a collar 27. The collar 27 supports a movable part of a door controlling means later to be described. Slidably mounted about the pipe 25 is a cylindrical weight 29 supported in spaced relation above the collar 27 by a spring 30, which spring 30 cushions the weight 29 when the weight 29 is suddenly accelerated by the cable 22.

The weight 29 and the suspended portion of the door controlling means are slidably mounted for movement in a vertical or first direction in the cylinder 15 which cylinder 15 is fixed against movement in the first or vertical direction. The tension thus provided in the cable 22 provides means for urging the door to a closed position and means to urge the follower 19 toward the nip of the two sheaves 18 to a first position of the follower 19 when the door is in the closed position. When a force sufficient to open the door 10 is applied to the door 10, the follower 19 is caused initially to traverse a section of the periphery of the sheave 18 located on the side of the door 10 toward which the door 110 is opened. This traversal causes the follower 19 to move away from the axis of the door 10 to a second position along the path of the follower 19 on door 10 in addition to being moved through the are traced by the second position of the follower on the door 10 as the follower 19 draws the cable 22 about the sheave 18. Thus, during the first segment of the opening of the door\10, the weight 29 is lifted at a rate greater than the rate at which the Weight 29' is lifted during the subsequent or second segment of the opening of the door during which the weight is lifted only by drawing the cable 22 about the appropriate sheave 18. Proportionally greater torque is therefore required to accomplish the greater rate of lift of the weight 29 during the comparatively short first segment of opening than is required during the longer second segment of the door 10 opening movement. This difference in opening torque is desirable as the system can be designed to require a small torque and thus provide relative ease of opening of the door during the second segment of door opening, while requiring a relatively high torque to initiate opening of the door so that the door will remain closed against forces not intended to initiate opening of the door, such as wind loading.

The magnitude of the torque required to initiate opening of the door is a function of the total weight w suspended from the cable 22, of the angle a between a line drawn through the axis of the follower 19 and the axis of a sheave 18 and a line represented by the cable 22 when the follower is engaging the sheaves 18, and of the distance D from the axis of the door to the point of contact between the follower 19 and the sheave 18. The formula for the required torque, neglecting the friction, thus being:

T=D(W tan a) It will be noted that the torque required to initiate opening of the door 10 may be adjusted by varying any of the listed variables, such as the angle a, which angle may be varied by changing the diameters of the sheaves 18 or of the follower 19, or by changing the distances between the axis of the sheaves 18. Also, it can be seen from the formula that where the follower 19 is positioned farther into the nip of the sheaves 18 so that the angle on approaches 90, the torque required to initiate opening of the door 10 approaches infinity so it is clear that any practical desired value of initial opening torque can be obtained by proper manipulation of the variables.

Means are provided to prevent slack developing in the cable 22 as the door is opened or closed. This means comprises a spring 32 located within the pipe 25, which is attached between the enlarged end of the cable 22 and the opposite end of the pipe 25. The spring 32 will draw slack cable into the pipe 25 through the hole in the pipe cap 24 to keep the cable 22 in position on the sheave 1'8 and pulley 23 when it might otherwise be displaced, such as when the door 10 is manually closed at a rate faster than the rate the weight 29 can be lowered in the cylinder because of the door controlling means.

The door controlling means includes a fluid restriction means for controlling the speed at which the door can be moved to the closed position and a brake means for stopping the opening movement of the door and for locking 6 the door in an open position for a predetermined time against the operation of the means for urging the door to the closed position.

A part of the door controlling means provides means for controlling the rate at which the door 10 is moved to its closed position by the urging of the weight 29, while allowing the movable portion of the door controlling means to be freely raised With the weight 29 during the first and the second segment of the opening of the door 10. To accomplish this the controlling means includes a fluid or liquid contained in the cylinder 15 to approximately a level 33 (see FIG. 3), and a piston assembly 35 which is connected by a hanger means or tubular hanger 36 (which is illustrated as cylindrical) to the collar 27 so that the piston assembly 35 will move within the cylinder 15 when the door is opened or closed.

The hanger 36 is a tube into which two opposing axially extending, diametrically opposed slots 37 are milled. The slots 37 extend a distance less than the length of the cylindrical hanger 36 and are designed to allow vertical movement of the hanger 36 and the attached piston assembly 35 relative to the base section of a plunger assembly 38, which base section is fixedly attached between opposed internal surfaces of the cylinder 15. The design and function of the plunger assembly 38 will later be described. A plug 39 is attached within the bore of the tubular hanger 36, which plug 39 forms the bottom of a cup-like area 40 at one end of the hanger located below the slots 37, which cup 40 performs a function later to be described. The plug 39 also defines the boundary below which the piston assembly 35 is located. A set of leathers 41 attached to the periphery of the lower end of the hanger 36 form a liquid-tight seal between the piston assembly 135 and the internal walls of the cylinder 15. The leathers 41 form, together with the felt washer 26, a guiding means to direct movement of the piston assembly 35 within the cylinder 15.

Formed in the piston assembly area 35 are passageways which allow liquid to flow through the piston assembly 35 so that the piston assembly 35 and hanger 36 can freely move inside the cylinder 15 while being drawn upward by the cable 22 attached to the door '10-and which passageways restrict the rate of fluid flow from the bottom side to the top side of the piston assembly 35, thereby restricting the lowering of the weight 29, hanger 36 and piston assembly 35 towards the bottom of the cylinder 15 during the closing of the door 10. The liquid used in the cylinder '15 should be one with a relatively constant viscosity over a temperature range of to -5 0 R, such as aircraft hydraulic fluid, so that the rate of movement of the indicated apparatus through the liquid will be consistent over the indicated range of temperatures.

As is best seen in FIGS. 3 and 5, the aforementioned passageways are comprised of holes 43 bored through the walls of the hanger 36 in the piston assembly area 35 so that fluid may pass into a cavity within the hanger 36 below the plug 39. In the aforementioned cavity is mounted a poppet valve 44, which is biased by a spring 45 towards a closed or seated position relative to a seat formed in a seat block 46 attached to the lower end of the hanger 36. The spring 45 is supported by a spring support housing 42 attached below the block 46, which support housing 42 has passageways to permit the thru-flow of liquid. The valve 44 is held olf its seat by an adjustable screw 47 which is tapped into the stem of the valve 44 and which screw 47 may be adjusted to bear against the bottom of a cylindrical cavity in the bottom side of the plug 39 in which cylindrical cavity the stern of the valve 44 is guided. When the piston assembly 35 is drawn by the cable in an upward direction the liquid within the cylinder 15 above the piston assembly 35 passes through the holes 43 and the weight of the liquid column above the valve 44 pushes against the head of the valve 44 to open the valve 44 against the light resistance of spring 45, thus allowing relatively free passage of the liquid through the piston assembly 35 into a cavity formed below the piston assembly 35 in the cylinder as the piston assembly is raised. When subsequently the weight 29 urges the door 10 to a closed position and urges the piston assembly 35 towards the bottom of the cylinder 15, the valve 44 is urged towards a closed position by the spring and by the pressure caused in the liquid in the cavity in the bottom of the cylinder 15. Flow of liquid through the valve 44 is restricted to the flow permitted through the valve as determined by the distance the valve 44 is held off its seat by the screw 47. Thus the lowering of the piston assembly 35 and the weight 29 towards the bottom of the cylinder 15 is controlled to a predetermined adjustable rate.

The door controlling means also provides a brake means activated only by forces acting to open the door 10 for braking or retarding opening movement of the door 10 beyond a predetermined open position or predetermined angular relationship with the frame 12, for stopping the door 10 at the open position, and for locking the door 10 in the open position for a predetermined period of time after the opening force on the door !10 has ceased, thus retaining said door in the open position for a predetermined time against the means urging the door 10 to the closed position. The means for activating the brake means upon an opening force being applied to the door 10 are so designed that the opening force applied to the door and/ or the opening momentum of the door provide the energy to activate the brake means.

The brake means accomplishes two functions. The first function is that of restricting or braking, within limitations, the opening motion of the door '10 beyond the aforementioned predetermined angular relationship with the frame 12. This restriction of motion is accomplished through use of a hydraulic actuating means or a dash pot means comprising the cup 40 full of liquid and a plunger 48. The dash pot means and the plunger 48 are connected to the door 10 to provide relative movement between the cup 40 and the plunger 48 upon movement of the door 10, and are positioned so that the movement of the door 10 to the aforementioned predetermined angle will cause the hanger means including the cup 40 to move from its normal or first position to a second position where the plunger 48 enters the cup 40 thus limiting or retarding further relative movement by placing the liquid in the cup 40 under pressure and displacing quantities thereof for actuating a mechanical brake means to further retard opening movement.

The second function of the braking means is to lock or retain the door 10 in an open position for a predetermined time after the opening swing has stopped for purposes such as allowing a person and/or vehicle to pass through before the door again begins to close. The mechanical brake means, activated by hydraulic pressure developed in the dash pot means when the opening move ment of the door 10 is restricted, is used for this purpose. Means is provided for delaying the release of the mechanical brake means after there is no longer pressure in the dash pot means, thus causing the delayed closing of the door 10.

As seen in FIGS. 3 and 5, the plunger assembly 38 supports the cylindrically shaped plunger 48 which is attached to a concentric tubular stem extending from the base section of the plunger assembly 38, which base sec tion extends transversely between, and is fixedly attached to, the interior walls of the cylinder 15. The plunger 48 is sized and positioned to enter the cup 40 in the hanger 36 with a minimum amount of clearance when the hanger 36 is (lI'BJWI'l upward via the cable 22. by the opening movement of the door 10.

A pressure control means is provided to establish the minimum speed of movement of the plunger 48 into the cup 40 which will cause sufficient pressure in the liquid in the cup 40 to operate the brake means, thereby establishing a minimum angular speed of opening of, the door 10 required when the plunger 48 enters the cup 40 to activate the brake means. Referring now to FIG. 5, one or more restricted liquid bypass means may be provided in the plunger 48. As illustrated, the bypass means is a ball bypass and check valve 55 comprising a ball 57 and a spring 58 enclosed in a cylindrical passageway 59 extending vertically through the head 48. The ball 57 is normally positioned on the top of the spring 58 and spaced from a seat formed in the uppermost end of the passageway 59. Thus, liquid may flow through the passageway 59 when the head 48 enters the cup 40' at a slow rate of speed; however, above a predetermined rate of speed the rate of liquid flow past the ball 57 will lift the ball 57 against the seat to block any further escape of fluid from the cup 40 through the passageway 59. Thus, if the rate at which the cup 40 is drawn over the plunger 48 is above a predetermined speed, the seating of the ball 57 will allow a pressure buildup within the liquid in the cup 40, which pressure is limited by a pressure relief valve 49. The pressure established in the cup 40* will cause a tensile force to be transmitted through the cable 2'2, which force will retard further opening of the door 10. The force so transmitted will be proportional to the pressure in the liquid and to the internal horizontal cross-sectional area of the cup 40'.

The pressure relief valve 49, best seen in FIGS. 5 and 6, provides further pressure control means for establishing a maximum pressure possible in the liquid in the cup 40 'when the plunger 48 enters the cup 40, thereby establishing the maximum pressure which may be developed in the liquid in the cup. 40 at any speed of opening of the door 10 to limit the swing of the door 10 by activating the brake means. This feature provides uniformity in operation for the system, and provides a safe upper limit for the forces which will be transmitted from the dash pot means through the cable 22 to brake the swing of the door 10, and for the forces transmitted to the mechanical brake, brake, stop, and lock the door in the open position.

The pressure relief valve 49 comprises 'a ball 50 mounted in a cylindrical passageway 52 formed vertically through the plunger 48. The ball is biased by a spring 54 towards a seat formed in the lowermost end of the passageway 52. The spring rate of the spring '54 is selected to effectively limit the maximum pressure which can be developed in the liquid in the cup 40 when the cup 40 and the plunger 48 engage. Pressures in excess of a predetermined maximum will lift the ball 50 from its seat against the bias of the spring 54, allowing liquid trapped in the cup 40 to flow around the ball 50 and through the passageway 52, thus limiting the pressure attainable in the liquid in the cup 40.

The valve 55 also allows liquid to be drawn into the cup 40 through the plunger 48 when the plunger 48 and the cup 40 are separated during the closing of the door 10. As the plunger 48 is raised, the ball 57 drops away from its seat against the top of the spring 58 and allows the liquid to flow through the passageway 59 into the cup 40.

The brake actuating means for the mechanical brake means includes means for delaying the release of the mechanical brake means until a predetermined time after the opening force has ceased so that the door will not start to close for a predetermined time. Referring now to FIGS. 2 through 6, the plunger assembly 38 is formed with a port 60 through which liquid may be caused to flow by pressure established in the cup 40. The port 60 extends from the lowermost face of the plunger 48, through the stem, and out one side of the base section of the plunger assembly 38, where, through a clearance hole in the cylinder 15, a valve and a hydraulic line 61 connect the port 60 with a cylinder 62. In the cylinder 62 a piston supporting a rod 63 is contained. The rod 63, by its position, may proportionally activate the mechanized brake means. The valve 65 is of the type which allows free flow of liquid in one direction :while providing an adjustable restricted flow of liquid in the opposite direction.

In the apparatus of. the present invention, the valve 65 is positioned so that liquid will freely flow through the plunger assembly 38 toward the cylinder 62; however, fluid returning from the cylinder 62 through the plunger 48 may be adjustably restricted to a predetermined rate of flow. Thus, after liquid is caused by pressure in the cup 40 to flow into the cylinder 62, thus extending the rod 63 to activate the mechanical braking means, the adjustable valve 65 will provide a desired rate of deactivation of a mechanical brake device 67 by regulating the rate of retraction of the piston rod 63 into the cylinder 62. Thus, the mechanical braking means, illustrated as the braking device 67, may be caused to lock the door in an open position until such predetermined time as the bra-king device 67 is sufficiently deactivated by bleeding of the liquid through the valve 65 that the weight on the cable 22 may move the door 10 towards a closed position against the retarding friction of the braking device 67 As best seen in FIGS. 2. and 4, the mechanical braking device 67 comprises a stationary brake member in the form of a semicircular plate 68 fixedly attached to the frame 12 and so located that the axis of the plate 68 is coincident with the axis of the bearings 16 about which the door '10 swings. An opposed friction brake device or clamping means is attached to the door. The braking force exerted by the clamping means on the plate 68 is proportional to the degree of extension of the rod 63. The clamping means is located so that it may exert clamping pressure on the arcuate plate 68 from any angular position of the door 10 with respect to the frame 12. Thus, the clamping means, when activated by extension of the rod 63, will cause a frictional retarding force between the arcuate plate 68 mounted on the door frame 12. and the clamping means to brake and stop free swinging of the door 10.

The clamping means includes an L-shaped jaw 69 movably supported between the side panels of the door 10 by pins on the door 10, which jaw 69 has a pad of suitable frictional braking material such as asbestos attached to its lower surface to rest against and contact the uppermost surface of the plate 68. An L-shaped movable jaw 70 is supported by and slidably mounted relative to the jaw 69 to move in a normally vertical direction. The movable jaw 70 has a pad of suitable braking material supported on its upper-surface to make contact with the lowermost surface of the plate 68 in opposed relation to the pad attached to jaw 69. A spring 71 is positioned between a shelf 72 attached to the jaw 69 and the lowermost side of the jaw 70 so that the jaws 70 and 69 are urged into contact with the arcuate plate 68, thereby providing a constant light drag between the arcuate plate 68 and the jaws 69 and 70 when they are moved relative to the plate 68. A rod 73, guided by a hole through the shelf 72 and having its end inserted in a depression in the lowermost surface of the movable jaw 70, is supported in a depression on an arm 74, which arm 74 is pivotably mounted by a pin 75 supported on the jaw 69. The end of the arm 74 opposite the pin 75 is supported upon the uppermost end of the piston rod 63 which extends from the cylinder 62. Thus, when the rod 63 is further extended from the cylinder 62 by liquid forced under pressure from the cup 40, the arm 74 moves the rod 73 to lift the movable jaw 70 relative to the jaw 69 so that firmer contact is made between the pads of braking material on the jaws 69 and 70 and the brake plate 68. The clamping action thus caused establishes a corresponding frictional drag between the braking material on the jaws 69 and 70 and the brake plate 68 so that the swinging action of the door 10 will be restricted or stopped.

OPERATION When the swinging door 10 is in a closed position within the frame 12, the suspended weight 29, hanger 36, and piston assembly 35 provide a weight which via cable 22 urges the follower 19 into the nip between the sheaves 18. A torque sufiicient to start the opening of the door 10 will force the follower 19 to traverse a section of the periphery of the sheave 18 located on the side of the door 10 toward which the door 10 is opened during the first segment of the door opening. The movement of the follower 19 about the appropriate sheave 18 mounted on the frame will also cause the follower 19 to move along its path on the door 10 in a direction away from the axis of the door 10, and thus for an equal speed of opening of the door 10 there will be required a torque capable of lifting the weight suspended by the cable 22 at a rate greater than the rate at which the weight will be lifted when subsequently the cable 22 is only pulled across an are traced by the position the follower 19 assumes on the door 10. Therefore, there is required to initially open the door 10, while the follower 19 rounds the sheave 18, a torque of a larger magnitude than the torque subsequently required to continue opening the door at an equal speed.

As the door opens, the piston 35 is drawn up through the liquid in the cylinder 15, and the flow of liquid opens and passes through the valve 44 on the piston assembly 35 from the area above the piston assembly 35 to the cavity being created below the piston assembly 35. The door 10 will thus be essentially freely opened until the door 10 is opened to the angular relationshhip with the frame 12 where the cup on the hanger 36- engages the plunger 48.

If the cup 40 filled with liquid is drawn onto the plunger 48 (as shown in FIG. 5) at a sufficiently slow rate of speed, due to a slow opening of the door 10, the liquid in the cup '40 will escape through the plunger 48 via valve without lifting the ball 57 to its seat so that a significant pressure will not be established in the liquid within the cup 40. If, however, the force propelling the door or the momentum remaining in the opening door 10 causes the cup 40 to be drawn over the plunger 48 at a speed greater than the predetermined minimum rate, the flow of liquid through the valve 55 will seat the ball 57 in the uppermost end of passageway 59 so that a pressure limited as to a maximum possible value by a pressure relief valve 49 in the plunger 48 will be developed in the liquid in the cup 40. The pressure in the cup 40 will tend to resist the movement of the cup 40 onto the plunger 48. This resistance will be transmitted through the cable 22 and will slow or break the opening of the door'10. Any pres sure in the cup 40 will also force liquid into the cylinder 62 thus extending the rod 63 to activate, in proportion to the magnitude of the pressure, the mechanical braking device 67. Activation of the mechanical braking device 67 causes the jaws 69 and 70 mounted on the door 10 to exert braking pressure on the brake plate 68, which plate 68 is mounted on the door frame 12. Thus, a retarding frictional force is caused between the jaws 6-9 and 70 and the brake plate 68 brake or to restrict further swinging of the door 10 and stop the door 10 in the open position. The fluid forced into the cylinder 62 by pressure in the cup 40 is restrained from leaving the. cylinder, even after pressure in the cup 40 is reduced, bythe restriction valve 65, which valve provides adjustable restriction of flow in the direction of flow from the cylinder 21 through the plunger assembly 38. Thus, the position of the rod 63, which position proportionally activates the mechanical braking device 67, may be maintained for a predetermined period of time to delay closing of the door 10. After the weight on the cable 22 has overcome the remaining frictional retarding forces applied by the mechanical braking device 67, the door will begin to close. The door will be retarded its closing, in addition to any remaining braking action by the mechanical braking device, by the restriction of the flow of liquid from the bottom side to the upper side of the piston assembly 35 through the valve 44. When the weight 29 and parts connected thereto have again urged the door 10 to its closed position, the follower will be positioned between the sheaves 18 thereby holding the door 10 in its closed position until the minimum required torque is again supplied to initiate its opening.

Having thus described the invention with reference to a preferred embodiment, what is claimed is:

1. A door assembly comprising: a door; a door frame for said door; means for attaching said door to said door frame so that said door may be supported by said frame and moved between a closed and an open position in relationship to said door frame; and a door checking and controlling device coupled between said door and said frame comprising: means for urging said door to said closed position within said door frame; and brake means activated only by forces moving said door toward said open position for braking the opening movement of said door beyond a predetermined relationship with said door frame, for stopping said door at said open position, for retaining said door in the open position for a predetermined period of time after the opening force on said door has ceased and subsequently releasing to allow movement of said door to said closed position by said urging means. 2. A door assembly according to claim 1, wherein said brake means comprisesi dash pot means affording a braking force upon opening movement of said door beyond said predetermined relationship between said door and said frame; mechanical brake means cooperating with said dash pot means for applying a frictional braking force upon opening movement of said door beyond said predetermined relationship to stop said door at said open position, said mechanical brake means being activated by fluid pressure caused in said dash pot means when the opening movement of said door is braked; and means for delaying the release of said mechanical brake means until a predetermined time after the pressure in said fluid in said dash pot means has ceased to retain said door in said open position for a predetermined period of time after the opening force on said door has ceased. 3. A door assembly according to claim 2., wherein said dash pot means comprises:

a cup; a fluid contained within said cup; a plunger adapted to enter said cup; means for connecting said plunger and said cup between said frame and said door to provide relative movement between said cup and said plunger upon opening movement of said door and to cause said plunger to enter said cup when said predetermined relationship exists between said door and said frame; pressure control means for establishing the minimum rate of movement of said plunger into said cup which will cause suflicient pressure in said fluid to operate said brake means and for establishing a maximum pressure developable in said fluid in said cup when said plunger enters said cup, thereby establishing a minimum opening speed of said door when said plunger enters said cup to afford a braking pressure in said cup, and establishing the maximum braking pressure in said cup to activate said brake means. 4. A door assembly according to claim 3, wherein said pressure control means comprises:

restricted fluid bypass means for allowing fluid to escape from said cup as said plunger enters said cup at a rate below a predetermined minimum rate and for restricting escape of fluid when said plunger enters said cup above said predetermined minimum rate to place said fluid in the cup under pressure for actuating said brake means, thereby establishing the 12 minimum speed of opening of said door required when said plunger enters said cup to cause sufficient pressure in said fluid in said cup to activate said brake means; and

a pressure relief valve means for allowing escape of fluid from said cup if pressure placed on said fluid reaches a predetermined maximum desired pressure.

5. A door assembly according to claim 4, which further comprises:

means for controlling the rate at which said door is moved to its closed position by said urging means.

6. A door assembly according to claim 1, further including means for retaining the door in the closed position, said retaining means comprising:

a follower mounted on said door for movement from a first position to a second position along a path essentially normal to the direction in which said door moves;

means for urging said follower toward said first position; and

cam means fixed on said door frame and abutting said follower for causing the movement of said follower from said first position at which said follower is positioned when said door is closed to said second position of said follower when force sufficient to open said door is applied to said door.

7. A door assembly according to claim 5, further including means for retaining the door in the closed position, said retaining means comprising:

a follower mounted on said door for movement from a first position to a second position along a path essentially normal to the direction in which said door moves;

means for urging follower toward said first position; and

cam means fixed on said door frame and abutting said follower for causing the movement of said follower from said first position at which said follower is positioned when said door is closed to said second position of said follower when force sufiicient to open said door is applied to said door.

8. A door assembly according to claim -7, wherein said door is attached to said door frame for rotation about an axis in either of two directions from said closed tosaid open position; said cam means for causing the movement of said follower from said first position to said second position is comprised of a pair of sheaves rotatably mounted on said frame, the axes of said sheaves being equal distant from and parallel tothe axis about which said door swings, said sheaves being spaced equally one on each side of said door when said door is in the closed position; said urging means for said follower comprises:

a weight;

a cable connecting said weight to said follower; and

guide means for said cable to position said Weight for movement in a vertical direction, and to pass said cable through the nip of said sheaves generally perpendicular to the axis of said sheaves so that in the closed position of said door said weight will urge said follower toward the nip of said sheaves to the first position of said follower; and

when said door is opened said follower moves in a direction away from the axis of said door, against the bias of said weight, in moving from said first position to said second position of said follower as said follower traverses a section of the periphery of the sheave located on the side of said door toward which said door is opened.

9. A checking and controlling device adapted for coupling between a door and a door frame for controlling the movement of said door with respect to said door frame between a closed and an open position, said check ing and controlling device comprising:

means for urging said door to said closed position within said door frame; and

brake means activated only by forces moving said door toward said open position for braking the opening movement of said door beyond a predetermined relationship with said door frame, for stopping said door at said open position, for retaining a said door in the open position for a predetermined period of time after the opening force on a said door has ceased and subsequently releasing to allow movement of said door to said closed position by said urging means.

10. A checking and controlling device according to claim 9, whereinsaid brake means comprises:

a support frame adapted to be fixed against movement in a first direction;

a hanger supported by said support frame for movement in said first direction from a first position to Ibeyond a second position and adapted for connection to said door so that said second position corresponds to said predetermined relationship between said door and said door frame; and so that said hanger will move from said first position to beyond said second position in response to motion of a said door from the closed to the open position, and said connection will afford the transmission of applied forces between said hanger and a said door to control movement of a said door;

a dash pot comprising:

a cup;

a fluid contained in said cup; and

a plunger adapted to enter said cup; said dash pot being connected between said hanger and said support frame so that said plunger will enter said cup when said hanger reaches said second position upon movement from said first position, thus retarding movement of said hanger beyond said second position because of pressures developed in said fluid in said dash pot and thereby braking further opening movement of a said door;

mechanical lbrake means cooperating with said dash pot for applying a frictional braking force upon opening movement of said door beyond said predetermined relationship to stop said door at said open position, said mechanical brake means being activated by fluid pressure caused in said dash pot when the opening movement of said door is braked; and

means for delaying the release of said mechanical brake means until a predetermined time after the pressure in said fluid in said dash pot has ceased to retain said door in said open position for a predetermined period of time after the opening force on said door has ceased.

11. A checking and controlling device according to claim 10, wherein said dash pot further comprises:

pressure control means for establishing the minimum rate of movement of said plunger into said cup which will cause sufiicient pressure in said fluid in said cup to operate said brake means and for establishing the maximum developable pressure in said fluid in said cup to operate said Ibrake means, said .pressure control means thus establishing the minimum speed with which said door must be opening at said predetermined relationship with said frame to activate said bra'ke means and establishing the maximum pressure which may be developed in said dash pot at any speed of opening of said door.

12. A checking and controlling device according to claim 11, wherein said pressure control means comprises:

restricted fluid bypass means for allowing fluid to escape from said cup as the plunger enters said cup at a rate below a predetrrnined minimum rate and for restricting escape of fluid when the plunger enters said cup above said predetermined minimum rate to place said fluid in the cup under pressure for actuating said brake means; and

a pressure relief valve means for allowing escape of fluid from said cup if pressure placed on said fluid reaches a predetermined maximum desired pressure.

13. A checking and controlling device according to claim 12, which further comprises:

means for controlling the rate at which said means adapted for urging a said door to the closed position may move a said door to the closed position.

14. A checking and controlling device according to claim 9, further including means adapted to retain a said door in the closed position, said retaining means comprismg:

a follower adapted for movement from a first position to a second position along a path on a said door, said path oriented essentially at a right angle to the direction in which a said door moves;

means for urging said follower toward said first position; and

cam means abutting said follower for causing the movement of said follower from said first position to said second position of said follower when said follower is moved essentially at right angles to said path by the opening movement of a said door, said cam means being adapted to be attached to a said door frame.

15. A checking and controlling device according to claim 13, further including means adapted to retain a said door in the closed position, said retaining means comprising:

a follower adapted for movement from a first position to a second position along a path on a said door, said path oriented essentially at a right angle to the direction in which a said door moves;

means for urging said follower toward said first position; and

cam means abutting said follower for causing the movement of said follower from said first position to said second position of said follower when said follower is moved essentially at right angles to said path by the opening movement of a said door, said cam means being adapted to be attached to a said door frame.

1 6. A door checking and controlling device according to claim 1'5, wherein said cam means for causing the movement of said follower from the first position to the second position comprises a sheave adapted to be rotatably mounted on a said door frame, said sheave being positioned so that said follower will traverse a portion of the periphery of said sheave when said follower moves from said first to said second position;

and wherein said urging means for said follower comprises:

aweight;

a cable connecting said weight to said follower;

and

guide means for said cable to position said weight for movement in a vertical direction while allowing said cable to extend from said follower in the plane defined by the periphery of said sheave.

17. A checking and controlling device according to claim Q, wherein said brake means comprises:

dash pot means affording a braking force upon opening movement of said door beyond said predetermined relationship between said door and said frame;

mechanical brake means cooperating with said dash pot means for applying a frictional braking force upon opening movement of said door beyond said predetermined relationship to stop said door at said open position, said mechanical brake means being activated by fluid pressure caused in said dash pot means when the opening movement of said door is braked; and

means for delaying the release of said mechanical brake means until a predetermined time after the pressure in said fluid in said dash pot means has References Cited ceased to retain said door in said open position ror UNITED STATES PATENTS a predetermined period of time after the openlng force on said door has ceased. 1,850,333 5/1932 P 16-81X 18. A checking and controlling device according to 5 3,274,733 9/ 1966 3 49-487 claim 9, wherein said brake means comprises: 3,295,589 1/ 1967 Pflegef et a1 means operating upon movement of a said door beyond 3,449,789 6/1969 Russell at 16-49X said predetermined relationship with said frame 3;4901175 1/1970 Romberg 49-364 for generating a braking force; and means adapted for connection to said door and operated 10 KENNETH Primary Exammer by said braking force for applying a frictional brak- U S C] X R ing force between said door and said frame to stop 16 51 further opening of said door.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3, 5, 3 Dated September 20, 1.971

flohn E. Nolan and Rudolph J. Wiplinger It is certified that error a ppears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 8, line 37, change "brake, brake" to insert brake means, to brake --3 Column 10, line 55, after "68", insert to ---3 and after "or" delete to --5 Column 12, line 3 L, after "urging" insert said Signed and sealed this lLLth day of March 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOITSCHALK Attesting Officer Commissioner of Patents RM PO- 1 050 (10-69) USCOMM-DC 50376-P59 u 5 GOVERNMENT PIIMYlur: an. .M. I n 

